This invention concerns a group of elements that comprises both a vehicle movable on rails and supporting means comprising said rails.
As an example, a train that travels on normal rails can be considered. The position of the centre of the gravity depends upon the size of the train and upon other factors and may be at any height, but always above the wheels.
If, in particular, a `double-decker` train is considered, that is a train comprising both an upper deck and a lower deck, each one suitable for accommodating people and/or goods (or similar), the centre of gravity will be located fairly high with respect to the rails on which the train travels. Therefore in such cases, so as not to risk the stability of the train, its speed cannot exceed a certain limit.